The present invention generally relates to gas turbine engines and more particularly, to the maintenance of compressor liner segment spacing.
A typical aircraft gas turbine engine includes a compressor for pressurizing air which subsequently is mixed with fuel and ignited in the combuster section with the resulting combustion gases powering the turbine. The compressor and turbine are surrounded by casings or liners through which air is either extracted or distributed.
In a typical compressor, an inner casing or liner is concentric with an outer casing and mounts stator or variable vanes. The inner liner also surrounds the rotor blades of the compressor.
The inner compressor liner is formed in segments around the circumference of the compressor. Because the liner is segmented, it allows recirculation leakage in between the segments which in turn reduces compressor performance. In order to reduce this leakage, spline seals are added between the liner segments.
Gaps between the liner segments wherein the spline seals are located are determined by the thermal expansion of the liner segments, and can be as large as approximately 0.05 inches. Because the gaps between the liner segments are required to be large to compensate for thermal closedown of the liner segments, keeping the spline seals engaged between the liner segments and functioning properly has become problematic. In order to solve the problem of maintaining the spline seals in between the liner segments, radial bolts have previously been used to fasten the liner segments to the outer casing to maintain uniform spacing between the liners. However, radial bolts require reinforcement on the outer casing and also on the liners to maintain the structural integrity of the compressor. This additional reinforcement adds weight and complexity to the design, as well as making it more difficult for assembly and disassembly. Therefore, a need exists for an improved method of maintaining uniform spacing between compressor liner segments that eliminates the problems associated with radial bolts, that is inexpensive to manufacture and easy to install.